The study – a meta-analysis of previous research published in Clinical Nutrition – investigated the relationship between habitual dietary salt intake and the risk of gastric cancer using data from nearly 270000 people. Using data from seven previous studies, the researchers reported to find “a graded positive association between salt consumption and incidence of gastric cancer.”
“Our pooled estimates indicate that habitual ‘high’ and ‘moderately high’ salt intake are associated with 68% and 41% greater risk of gastric cancer, respectively, compared with ‘low’ salt consumption,” said the research team, led by Professor Pasquale Strazzullo, from the University of Naples Federico II.
Speaking with FoodNavigator, Professor Graham MacGregor of the Wolfson Institute of Preventive Medicine, UK, and Chairman of Consensus Action on Salt and Health (CASH) said that whilst the findings of the study are not new, what it does do is confirm “in a very well done study” that previous findings are correct.
“My own view is that it’s getting to the stage where we can say that it is almost certainly causative,” said MacGregor, who added that the meta-analysis offered further evidence for the mechanisms behind salt’s effect on gastric cancer.
Salt – some but not too much
Sodium is of course a vital nutrient and is necessary for the body to function, but the average daily salt consumption in the western world, between 10 and 12 grams, vastly exceeds maximum recommendations from WHO/FAO of 5 grams per day to control blood pressure levels and reduce hypertension prevalence and related health risks in populations.
In countries like the UK, Ireland, the USA, and other industrialized countries, over 80% of salt intake comes from processed food, and people therefore do not realize they are consuming it.
Previous research has suggested that increased consumption of salted foods could increase the risk of certain cancers – including gastric cancer.
“In general, the detection of statistical associations in prospective studies provides stronger support to the possibility of a cause–effect relationship; however, in the case of excess salt intake and risk of gastric cancer the cohort studies available did not show consistent results,” explained Strazzullo and his team.
“For this reason, we carried out a systematic review and meta-analysis of these studies to evaluate the association between habitual levels of dietary salt intake and risk of gastric cancer and to obtain an estimate of risk.”
The process of reducing salt levels in foods is an ongoing process within the industry, with many now acknowledging that high sodium levels in some foods is a major issue for the industry.
Strazzullo and his colleagues explained that population reduction in salt intake –recognised as a global priority – through many avenues, including industry reformulation, has been suggested for the prevention of cardiovascular disease both in developed and developing countries.
“Although our results do not conclusively prove a causal relationship between excess salt intake and risk of gastric cancer, they do suggest the potential for further benefit by this policy in addition to its effects on cardiovascular morbidity and mortality,” they said.
MacGregor said that the latest findings “give another angle to salt reduction,” explaining that it adds into other evidence on cancer and cardiovascular disease to show that “reducing salt intakes globally needs to be a priority.”
“I think if you talk to most people in the food industry, then they would say that so long as it’s a level playing field, and everybody has to do it together, then they don’t mind doing it,” he said.
However, as simple as taking out some salt in foods might sound, the challenges associated with reducing levels in food are intricate and have major challenges in reformulation.
Speaking to FoodNavigator previously, Dr Paul Berryman, CEO of Leatherhead Food Research, explained that reducing salt in foods is “a complex issue.”
“Salt reduction sounds easy, but it isn't!” said Berryman, adding that the effects of salt reduction on food safety and shelf life are a particular worry because of salts action as a preservative.
Source: Clinical Nutrition
Published online ahead of print, doi: 10.1016/j.clnu.2012.01.003
“Habitual salt intake and risk of gastric cancer: A meta-analysis of prospective studies”
Authors: L. D’Elia, G. Rossi, R. Ippolito, F.P. Cappuccio, P. Strazzullo